Directional radar detector control



3, 1966 J. R. ODION ETAL 3,268,863

DIRECTIONAL RADAR DETECTOR CONTROL Filed May 1, 1964 2 Sheets-Sheet 1 I 6 7 2K I f A 2 MlcRowAvE I MICROWAVE TRANS. a REC. I TRANS.& REC.

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5l 594 hsl SIGNAL AND ALARM cmcun INVENTORS JOHN R. ODION CHARLES L. DUVIVIER BY dbaaa mmo,

ATTORNEY Aug. 23, 1966 J. R. ODION ETAL 3,263,363

DIRECTIONAL RADAR DETECTOR CONTRQL Filed May 1, 1964 2 Sheets-Sheet 2 '1 I Low FREQUENCY HOLD CIRCUIT age .0 I I TMNG R 45 ISISEUFTREOUENCY INPUT I I l I ig IE I67 I35 I 360 e I I I47 I356 I I I &

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INVENTORS JOHN R. ODION CHARLES L.DUVIVIER BY 5200 w ATTORNEY United States Patent 3 268,863 DIRECTIONAL RADAR DETECTOR CONTROL John R. Odion, Wilton, and Charles L. Du Vivier, Darien, Conn., assignors to Laboratory for Electronics, Inc., Boston, Mass, a corporation of Delaware Filed May 1, 1964, Ser. No. 364,186 15 Claims. (Cl. 34039) This invention relates to radar units and associated circuitry for detecting direction of traflic flow in a lane in which alternate direction flow is possible. In particular, it relates to a detection or control system employing the Dopper effect of vehicle motion in beamed wave energy for detecting the actual direction of flow of traflic in a detection zone in a trafiic lane and further relates in one aspect to actuating a signal or other warning device to indicate or divert traffic moving in opposition to the established direction or against a red or stop signal.

In traflic systems there are many instances where a particular traflic lane may be used during some time for traflic in one direction, and other times for traflic in other directions. Examples of this would be the reversible center lane found on some express highways, bridges and tunnels, and the center passing lanes found on three-lane highways.

In such situations, signal lights or other devices may be set manually or automatically to allocate the reversible lane to a particular traflic direction. The lights would then remain in the set condition, so that the traffic would go only in one direction until manually changed, or the lights could be controlled by timing circuits to periodically change the direction of the lane. An intervening connection or setting without preference in direction of traflic flow is also sometimes provided as known in the prior art.

Under such circumstances, it is important that there be detection of direction of traflic flow and particularly detection of traflic flow against the direction established by signs or signals, and sufficient Warning signals to prevent passage of trafiic in the wrong direction.

In another aspect the invention may be employed to indicate or warm a vehicle or vehicular tralfic moving against a red or stop signal at an intersection controlled by traflic signals.

Accordingly, it is an object of the present invention to provide directional detecting means to determine the direction of actual trafiic flow in the established direction. This indication of traflic in the established direction will be continued by the circuitry of this invention until the detection zone in the lane is cleared of traflic and a sufficient time interval has passed for safety considerations.

It is a further object of this invention to detect the existence of a vehicle moving in a direction opposed to the established direction and to sound an alarm or give other signals to the vehicle.

It is a further object of this invention to provide such a system that will continue to indicate the latest direction of traffic flow even though there is congested traflic, causing traflic to proceed very slowly or even come to a halt and to maintain such indication until any such congested traffic has reached suflicient speed to indicate smooth trafiic flow again.

This invention may utilize much of the same circuitry used for radar speed checking and radar counting of traffic, thus, allowing for an economic installation. Since it uses radar or over-the-road reflected wave energy units, this invention avoids the problems such as cutting into or under the road and temporary blockage of traffic, for example, inherent in various under-the-surface detection units.

These and other advantages of the invention will become apparent from the accompanying drawings and description of the invention. The drawings are as follows:

FIG. 1 is a schematic drawing showing the arrangement of two radar detector units with reference to a traffic lane;

FIG. 2 is a generalized block diagram showing the circuitry used in this invention; and

FIG. 3 is a circuit diagram showing the details of the control circuits of this invention.

In FIG. 1 there is depicted a lane 1 of the type adapted to be used for traflic in either direction. There are designated two traflic directions A and B as shown by the respective arrows. Traveling on lane 1 in the A direction is vehicle 2. Mounted above lane 1 are two transmitting and receiving units 4 and 5, which may be in the form of one or more dipoles with directive reflector of the radar type or other conventional directive wave energy radiator and receiver. These units may be placed at any convenient separation distance and any height from the highway, but preferably they are positioned between six and eight feet apart and about fifteen feet above lane 1. The antenna or radiator-receiver units 4 and 5 are so directed that their respective beams 6 and 7 cover different portions of lane 1, preferably so that the inner edges of the beams, at half power points, are closely adjacent. As shown in FIG. 1, unit 4 has a beam 6 with its axis at a small angle to the vertical and along the lane toward the direction from which a car moving in the A direction would come, and the axis of the beam 7 of unit 5 correspondingly has a small angle in the opposite direction, toward the direction from which a car moving in the B direction would come. Normally, the angle of the two axes from the vertical would be the same, and preferably, would be about twenty degrees.

The radar units 4 and 5 are preferably Doppler radar units of the type generally described in Barker Patent No. 2,965,893, 'but providing separate amplification and direct current or relay outputs for low Doppler frequency and for high Doppler frequency, as further described below, and utilizing electromagnetic waves of a frequency of about 2400 megacycles for example, although supersonic air waves of high frequency of the order of 25,000 cycles per second may be used, for Doppler frequencies of about ten times those obtained by the 2400 rnegacycle radio Waves. Since the Doppler beat frequencies depend upon the speed of movement of vehicles, as reflectors or reradiators, relative to the radar unit, it can be seen that the Doppler frequencies obtained for a given vehicle speed will be lower or approach zero when the vehicle is almost directly under the radar unit, i.e. at a maximum angle, in the inner part of the beam .of radiated Waves and will be of greater frequency when the vehicle is farther removed from the radar unit, i.e. in the outer part of the beam. Thus, in FIG. 1 for a constant speed of motion of vehicle 2 in the A direction, the Doppler frequency will be greater when the vehicle is at the left, just entering the beam 6 of radar unit 4, than it will be when the vehicle is substantially underneath the radar unit. As the vehicle continues to pass in the A direction, and through the inner part of the first beam 6, it will cause lower Doppler beat frequencies through the radar unit of dipole 4. Then, as it continues to move farther to the right, through the second beam 7 it will cause low and then higher Doppler frequencies through the radar unit 5. In the past, these low and high Doppler frequencies have been distinguished by filter circuits and used for counting and speed determination respectively, as more fully disclosed in Barker Patent No. 3,059,232, for example.

In the present invention, by placing two radarunits with angled beams back-to-back in effect, and deriving distinctive pulse or relay outputs from the outer and Patented August 23, 1966- inner parts of the beams, from the high and low Doppler frequencies, the sequence of a low frequency output from a first of the two beams followed by a high frequency output from a second of the beams, as a vehicle proceeds at substantial speed through the beams, causes operation through interlocking relay circuitry, of a particular relay for a particular direction and release of such relay, but where the vehicle speed is quite low as in congested traflic, the particular direction indicative relay is held in to maintain the direction indication until after a vehicle passes at substantial speed through the beam.

FIG. 2 shows in block diagram form the circuitry of this invention. It can be seen that the circuitry is symmetrical and has as inputs the frequencies from the A and B radar units 4 and 5.

The circuit consists of two microwave transmitters and receivers and 11 associated with radar units 4 and 5, respectively. The output of each of the receivers of these units is a Doppler frequency determined as aforesaid. In the case of transmitter and receiver unit 10, the Doppler output passes through lead 13 to high frequency amplifier 14 and low frequency amplifier 15. These amplifiers may be tuned amplifiers or filter and amplifier combination for selected high and low frequency bands. The amplifier 14 has a band pass for Doppler frequencies ranging from 200 cycles per second to about 80 cycles per second, and amplifying the frequencies passed. The output of amplifier 14 then passes through lead 17 to actuate the coil of speed relay A, identified as 19. Low frequency amplifier is adapted to pass a frequency of about 10 to 20 cycles per second and to amplify same. The output of amplifier 15 passes through lead 21 into count relay A, identified as 22.

In a comparable manner, the Doppler output from microwave transmitter and receiver 11 from portion B of the circuit, passes through lead 28 into high frequency amplifier 29 and low frequency amplifier and filter 30. The output of high frequency amplifier 29 passes through lead 35 into the coil of speed relay B, identified as 36. The output of low frequency amplifier 30 passes through lead 38 into the coil of count relay B, identified as 39. These frequencies passed by amplifiers 29 and 30 are the same as the frequencies passed by the respective amplifiers 14 and 15 on the A side of the circuit.

Speed relays 19 and 36 each control timing circuit 45 as indicated by dotted lines 46 and 47 leading from relays 19 and 36 to this timing circuit.

Count relays 22 and 39 control direction locking circuit 51, as indicated by lines 49 and 50, respectively.

From a released condition initial actuation of relay 22 will set direction locking circuit 51 in the A direction; whereas initial actuation of relay 39 will set direction locking circuit 51 in the B direction.

Through the direction locking circuit, operation of count relay 22 before count relay 39 disables or locks-out the responsiveness of the direction locking circuit 51 to count relay 39; and operation of count relay 39 before count relay 22 disables or locks-out the responsiveness of the direction locking circuit 51 to count relay 22. This disablement occurs depending upon the direction of initial trafiic flow.

Timing circuit 45 serves to release the direction locking circuit from its direction indicating condition to normal released condition, at the end of a pre-determined time period, as indicated by line 55, respectively, after the timing circuit has been energized by speed relay 36 or speed relay 1'9.

Direction locking circuit 51 controls signal and alarm circuit 60, as indicated by lines 59 and 61 in response to signals received from relays 22 and 39 and the pre-determined trafiic flow direction set in the signal and alarm circuit 60, as will be described below.

Actuation of either relay 22 or relay 39 during the time period of timing circuit 45 serves to arrest the timing cycle as indicated by lines 56 and 57 respectively. It will not recommence operation until receipt of another signal from 4 either relay 19 or relay 36, with both relays 22 and 39 de-energized.

FIG. 3 discloses details of the circuitry of timing circuit 45, direction locking circuit 51, signal and alarm circuit 60, and their respective input circuits. The circuit of FIG. 3 has been broken up into generalized portions that are labeled to show their functions. These include the portions for timing circuit 45, direction locking circuit 51, and signal circuit 60. In addition, there are sections for low frequency input circuit 70, high frequency input circuit 72 and low frequency hold circuit 74. The various relays shown in FIG. 3 are depicted in their normal non-energized positions.

Low frequency input circuit includes relay coils 22 and 3-9 of FIG. 2 and associated relay contacts. Coil 22 is associated with input section A and coil 39 with input section B. Relay 22 includes grounded contact arm 22a, normally closed contact 22b, and normally open contact 220. Contact 22b is connected through lead 75 to neon indicator light 76, and then to ground, and also through resistor 77 to a source of positive potential. When contact 22b is closed, the positive potential source is, in effect, grounded through resistance 77 and the light 76 is off. When contact 22b is opened, the positive potential is applied through resistance 77 to light 76, and the light is on.

Comparably, relay coil 39 cooperates with contact arm 39a, normally closed lower contact 39b, and normally open upper contact 39c. Contact arm 39a is grounded. Lower contact arm 39b connects through lead 80 to neon indicator light 81 to ground and also through resistor 82 to a source of positive potential. With contact 39b closed, the positive potential is grounded through resistor 82 and lead 80, and light 81 is off, just as is the case with the A side of the circuit. When contact 39b is broken, potential is supplied to light 81 and it goes on in like manner.

Upper contact 220 associated with coil 22 is connected through lead 90 to contact arm 85a and to upper contact 85 of A direction indicative relay 85, and is also connected via line 97 to contact arm 86b of B direction indicative relay 86. Oomparably, upper contact arm 39c, associated with coil 39, is connected through lead 92 to contact arm 86a, upper contact 86f of relay 86 and via line 102 to contact arm 85b of relay 85.

Also controlled by relay coil 22 is grounded relay contact arm 22d which is normally closed and connected to contact 22c.

Comparably, coil 39 has associated with it contact arm 39d and normally closed contact 39e. Contact 22e is connected to contact arm 39d through lead 23. Thus, relay arms 22d and 39d are normally closed with their respective contacts and in series with ground.

Direction locking circuit 51 includes two direction indicative relays having coils 85 and 86 representing the A and B sides of the circuit, respectively. Coil 85 controls contact arms 85a, 85b and 850. Arm 85a has normally-open upper contact 85d. Arm 85b has normally-closed contact 85a and normally-open upper contact 85 Arm 85c has normally-open upper contact 85g. Comparably, coil 86 has contact arms 86a, 86b and 860. Arm 86a has normally-open upper contact 86d. Arm 86b has normally-closed lower contact 86:: and normallyopen upper contact 86]. Arm 86c has normally-open upper contact 86g.

Direction relay coil 85 is connected at one side to a source of positive potential, and at the other side is connected through lead 96 to lower contact 86e, associated With contact arm 86b, and normally closed. Contact arm 86b is connected through lead 97 and lead to upper contact 220. When contact arm 22a is raised to connect with contact 220, a circuit is completed from the source of positive potential through relay coil 85, lead 96, contact 86e, contact arm 86b, lead 97, lead 90, contact 220 and contact arm 22:: to ground. Thus, it can be seen that when relay coil 22 is energized, raising contact arm 22a,

this will serve to energize relay coil 85 (provided that contact 86b-86e is closed), and thus raise associated contact arms 85a, 85b, and 85c of relay 85.

The circuitry associated with the relay coil 86 is comparable. Coil 86 is connected to a source of positive potential and is connected through lead 101 to lower contact 85e, and normally closed contact arm 85b, leads 102 and 92 to normally-open contact 39c associated with relay coil 39. Thus, energization of coil 39 serves to complete a circuit from ground via contact 390 and as just described for actuation of relay coil 86. It can be seen that when relay coil 39 is energized, it will raise contact arm 39a to close the circuit with contact 390 and so energize coil 86, provided that contact 85b-85e is closed.

Energization of either coil 22 or coil 39 and actuation of the corresponding contact arms will cause the respective coil 85 or 86 not only to be energized but to be locked in its energized position. For example, when coil '85 is energized, contact arm 85a is raised to connect with contact 85d. Contact 85d is connected through lead 110, contact 115b, and normally-closed contact arm 115a to ground. Ground is also connected through contacts 115a,115b, contact 85d and cont-act arm 85a (when closed), through lead 97 to contact arm 86b, normallyclosed contact 86c, and lead 96 to coil 85. Thus, the raising of contact arm 85a through initial energization of coil 85 serves to lock relay 85 in the energized position under control by contacts 115a-115b. A comparable result is achieved with coil 86 when contact arm 86a is raised to contact 86d, if coil 86 is energized before coil 85. In this instance the circuit is completed from ground through contact arm 115a, contact 11512, lead 110, contact 86d, contact arm 86a, leads 120 and 102, contact arm 8512, contact 85c, and lead 101 to coil 86 and thence to a source of positive potential. So, comparably, once coil 86 is energized, relay 86 is locked into the energized position under control by contacts 115a-115b of relay 115.

Relays 85 and 86 are mutually interlocked, each through a normally closed contact of the other, so that when one is energized, this serves to block energization of the other. Thus, the circuit for initial ener-gization of coil 85 includes contact arm 86b and contact 862 of relay 86. As a result, if coil 39 representing the B side of the circuit is thereafter energized, the circuit from contact arm 39a and contact 39c through leads 92 and 102 to contact arm 85b, will be found not to be connected to contact 85c and coil 86 cannot be energized.

Also associated with coil 85 is contact arm 85c and normally-open contact 85g. When relay 85 is in operated position, this contact will be closed. This contact then can serve to control signal or alarm circuits. For example, if traffic was moving from the A direction in FIG. 1, thus serving to lock relay 85 in its energized position and close the contact between arm 85c and contact 85g, leads 125 and 126 associated with the contact 85g, and contact arm 85c would then be connected to gether to provide a direction indicating output for the A direction or to control other apparatus.

In a similar manner, contact arm 86c, in association with normally-opened contact 86g, is likewise controlled by relay coil 86 for similar output control purposes and has output leads 127 and 128. When coil 86 is energized, then the circuit between leads 12.7 and 128 will be closed to provide a direction indicative output for the B direction or to control other apparatus.

Output leads 125 and 126 correspond to output 59 and.

through lead 130, contact 39e, contact arm 39d, lead 23, contact 22a, contact arm 22d, and ground when both relays 19 and 22- are deenergized. Contact 19a is connected through lead 131 and 132 to the timing circuit control relay coil 135 and thence to a source of positive potential.

Operatively associated with relay coil 135 is normallyopen contact arm 135b, adapted to connect with contact 135a. Energization of coil 135 closes this contact and efiects a locking of the relay 135 in the energized or on position through lead 140, connected to lead 132 and lead 141 connected to lead and thence via contacts 39d- 39e and 22d-22e to ground. Thus, momentary energization of relay 19 results in the operation and locking of relay in the on position, when both relays 22 and 39 are deenergized, and thus relay 135 will be released if either of relays 22 and 39 is energized. Operation of relay 135 causes the timing circuit 45 to start timing as more fully described below.

The high frequency input for the B side of the circuit is applied to coil 36. Coil 36 is operatively associated with relay contact 36a and normally-open contact arm 36b. Contact 36a is connected to lead 132 and normally-open contact arm 36b is connected to lead 130. Thus, in a manner comparable to the actuation of coil 19, actuation of coil 36 can also energize coil 135 and lock it in the energized position.

Also associated with coil 135 is contact arm 1350 normally closed with grounded contact 135d. Upper contact 135e is normally open and cooperates with contact arm 135c. Contact 13542 leads through variable resistor 147 and resistor 148 to a source of positive direct current potential. Contact arm 1350 is connected through lead 150 and resistor 151 to one side of timing capacitor 152, the other side of which is grounded. The junction be tween resistor 151 and capacitor 152 is connected to the grid of the right hand section of double triode 155. In the normally down position of contact arm 1350, this grid of tube 155 is grounded through resistor 151 and lead 150 and contact 135d. This also grounds capacitor 152 through relatively low resistance 151.

When contact arm 1350 is in the up or energized position, positive direct current potential is applied through resistors 148 and 147, contact 135e, contact arm 135a, lead 150, and resistor 151 will serve to charge capacitor 152, thus raising the voltage on the capacitor and the right hand grid of tube 155. As can be seen, capacitor 152 in combination with resistors 151, 147 and 148, makes up an RC timing circuit. The period of timing is predetermined by setting variable resistor 147, which is a relatively high resistance, the timing period being of the order of one to five seconds for example.

Circuitry of double triode 155 is a trigger circuit of a type shown in P. C. Brockett Patent 2,964,625. Referring to the right-hand portion of dual triode 155, the cathode is connected to ground through resistor 160. The plate circuit extends through timing output relay coil 115 and thence through lead to a power supply circuit made up of a source of direct current potential, derived by rectification from alternating current source AG. by means of resistor 166, diode 167, and grounded capacitors 168 and 169. The direct current for charging the capacitor 152 is derived via line 171 tapped to a potential divider 172 connected between the first mentioned direct current source at line 165 and ground. The plate circuit of the right-hand triode section is also connected through lead 175 to resistance 176 and thence to the grid of the left-hand section of dual triode 155. This grid is also connected to ground through resistor 179 and parallel capacitor 178. The coil 115, resistor 176 and resistor 179 provide a voltage dividing circuit for adjusting the bias on the left grid of dual triode 155. The plate of the left portion of dual triode 155 connects through lead 182 to the aforesaid direct current source. There is a capacitor 183 between the two plate circuits. Operation of this triode in its trigger configuration will not be described herein since it is adequately described in the aforesaid Brockett patent.

Thus it can be seen that energization of relay coil 135 will close the contact between arm 135a and contact 1356, enabling the capacitor 152 to commence charging. At the time of closure, capacitor 152 had been discharged through contact 135d and so the right-hand section of dual triode 155 was at cut-01f with the left-hand section conducting. When the charge on capacitor 152 is sufiicient, the bias on the grid in the right-hand section of dual tube 155 will permit this triode section to conduct and, accordingly, will allow current to flow from the power supply through coil 115 and the plate of tube 155 to energize relay coil 115. The left-hand triode circuitry of tube 155 cooperates in providing a trigger circuit in accordance with the Brockett patent which accelerates this conduction once the capacitor 152 has reached the proper potential, the left section becoming cut-off to non-conduction when the right section becomes conducting in dual tube 155.

Energization of coil 115 then lifts normally closed con tact arm 115a and breaks the circuit for contact 1151). This, as previously described, de-energizes coil 85 or 86, depending upon which has been energized, by breaking the contact between contact 85 and arm 8512 or contact 861 and arm 86b, as the case may be.

Thus, as a vehicle enters beam 6 from the A direction and continues through the beam to provide a low tfrequency Doppler signal through radar unit 4 on input lines 21, this will energize relay 22 which serves to energize relay 85 and lock it in energized position. Subsequent similar actuation of relay coil 39 as the vehicle proceeds through beam 7 will not affect the relay 86 since it is locked out.

Actuation of relay 85 will close contacts 85g and 85c and so provide a directional indicative output for controlling and setting whatever indicator signal or other circuit is desired. Such signal or circuit will remain set until after the vehicle passes at substantial speed through the other end of the double detection zone and actuates the speed relay 36 by high frequency Doppler signal input through radar unit on lines 35. At that time, relay 36 will close contacts 36a and 36b to actuate relay coil 135, which starts operation of timing circuit 45. At the end of the timing period, relay coil 115 will be energized and open contacts 115a and 11%. This will de-energize coil 85 and release relay 85 and return the direction locking circuit to its original condition.

When a vehicle enters from the B side, there is comparable operation since the two circuits are mirror images, except that in this instance the initial actuation will be of relay coil 39 by low frequency input signal from radar unit 5 via lines 38 and therefore the relay 86 will be operated and lock in on position. Actuation will cease when the vehicle leaves at substantial speed through the outer part of A end of the dual detection zone after actuating speed relay 19 by high frequency Doppler signal on lines 17 through radar unit 4. Relay 19 will close its contacts 19a-19b to operate the timer control relay 135, so that after the time delay of timing circuit 45, the operation of its relay 115 will release relay 86.

The above description of operation assumes that but one car enters at a time and that this car leaves the entire radar controlled area before the next one enters and before the expiration of the time period for having another one enter. The low frequency hold circuit 74 is adapted to extend the period of controlled operation in the established direction in the event a second car enters the area or in the event vehicles are traveling slowly through the area or come to a stop in it. During the period that any vehicle is moving in the area covered by the count relay 22 (normally the inner part of the beam except for a very slow moving vehicle), relay coil 22 will be energized and, as described above, contact arm 22d in the low frequency hold circuit will be opened. This will open the circuit to timer control relay coil 135, thus de-energizing it. Whenever coil 135 is de-energized, contact arm 1350 will be in its normally down position in contact with grounded contact 135d. This will serve to ground capacitor 152 and so cut otf the right-hand triode portion of tube 155. Under such circumstances, coil will not be energized, so that the circuit of arm 115a and contact 1151; will remain closed, leaving the coil 85 in its locked energized position. comparably, the same operation also occurs when the direction established by the movement of the actuating vehicle is the B direction, with direction indicative relay 86 in the locked position. Under such circumstances the passage of any vehicle in the count relay 39 area will operate relay 39 and break the circuit between arm 39d and contact 39c, de-energizing relay 135 and thus bringing the timing cycle to an end in a similar manner. The timing cycle will only begin as the last car leaves the zone at substantial speed, thus actuating either speed relay 19 or speed relay 36, depending upon direction of travel. The time period will preferably be equivalent to that between closely spaced cars, that is, at least as great as the normally anticipated time spacing of cars in a lane under full tratfic condition.

Signal and alarm circuit 60 in the preferred form includes red signal 63 and green signal 67 for the A direction and red signal 65 and green signal 68 for the B direction. It also has B direction alarm 69 in series with control leads 127 and 128 and A direction alarm 62 in series with control leads and 126.

Switch 64 serves to connect the above with a source of positive potential and to pre-determine the desired direction of trafiic flow in lane 1 by setting the red and green signals for such desired direction in the lane for example. In the left-hand position illustrated, switch 64 connects the power source to lights 65 and 67 and, through control leads 127 and 128, to alarm 69 when contacts 86c-86g are closed.

In the right-hand position, switch 64 connects the power source to lights 63 and 68 and, through control leads 125 and 126, to alarm 62, when contacts 85c85g are closed. The lights, then, will operate upon closure of the switch 64 and show desired traific direction. One or the other of the alarms will operate only upon closure in addition of the respective contacts, above described, 85c and 85g for alarm 62, and 86c and 86g for alarm 69.

Thus, entry of a vehicle into lane 1 in the pro-established direction will not operate the alarm; entry in the opposed direction will operate the appropriate one of the alarms, indicating the direction of the violation.

Switch 64 illustrative of a switching means for lane reversing control and may be operated manually or by a program timer or in response to measurement of trafiic in the respective directions on a multi-lane road including some lanes permanently assigned to the respective directions, using the features of US. Patent 2,542,978 for example. The switch 64 may also have an intermediate neutral position 99 in which there is no pre-established lane direction and correspondingly no operation of the direction alarms 62 and 69.

In such case the indicator lamps or signals 87 and 88 would serve as an indication of direction of travel of any vehicle or vehicles proceeding in the beams 6-7. Thus indicator 87 is connected through a current limiting resistance 93 in parallel with relay coil 85 to indicate vehicle passage in the A direction regardless of any pre-established direction for the lane, and indicator 88 is connected through current limiting resistance 94 in parallel with the relay coil 86 to indicate vehicle passage in the B direction.

These indicators 87 and 88, although indicated schematically as neon lamps, may be of incandescent lamp type or other form of signal or annunciator, and may be located at or near the detection zone or at some remote point for monitoring the actual flow of traffic at the detection zone. Similarly the alarms 62 and 69 could be located at a remote monitoring point if desired or additional alarms or signals could be connected in parallel with alarms 62 and 69 to be operated therewith and to appear at a remote location.- Such alarms or signals 62 and 69 or such parallel connected additional signals or illuminable signs, such as arrows pointing toward the right for traffic in the respective directions, could serve to divert traflic actuating the detection system in a direction opposed to the pre-established direction. The system of the invention could also be used to indicate a vehicle moving against a red signal at a road intersection or other point controlled by trafiic signals, although it has particular significance in indicating vehicle movement separately in either of two directions, or in opposition to established control in either of two directions.

in the preferred form shown and described above, the timing output relay 115 remains energized, once operated on completion of timing, until another vehicle arrives in the detection zone and produces a low frequency Doppler signal, i.e. until one of the low frequency operated relays 22 or 39 is again operate-d.

Although the operation of relay 115 releases the direction locking circuit 51 and whichever one of the direction indicative relays 8 5 or 8 6 is operated, and thus also discontinues operation of whichever one of the alarms 62 or 6 9 is operated, nevertheless the timer control relay 1 35 remains locked energized over its own contacts, and the normally closed contacts of low frequency input relays 22 and 39', until one of these latter relays is operated by such arrival of another vehicle at low enough speed or within the inner part of the beam.

Thus, after the timer circuit has completed timing after passage of any one vehicle, and so long as no further low frequency input is received from any subsequent vehicle, the capacitor 152 continues to charge substantially to the voltage supply, thereby keeping the dual triode trigger circuit in the condition of conduction in the right section and nonconduction in the left section, and keeping relay 115 energized. This condition ends and the timing circuit returns to normal inactive condition as soon as relay 22 or relay 39 is operated by a subsequent vehicle.

The relay 22 (or 3-9) remains energize-d long enough to allow for release of relays 135 and 115 to re-establish the holding circuit via contact 1151) for proper operation of relays 85 or 86 respectively.

If it is desired to reset the timing circuit to normal along with release of the direction locking circuit, this may be provided for by a minor circuit modification by disconnecting contact 22d from direct ground and connecting this contact to line 110 to receive ground only Where contacts 1 1 5a-115b are closed, i.e. when relay 115 is de-energized, and thus operation of relay 115 at the end of the timing period would release relay 135 as well as the direction lock-ing circuit relay, and consequently relay 115 would also release at such time, without Waiting for arrival of another vehicle.

The preferred circuit shown is simpler and avoids an additional line from the contact 212d to the direction locking circuit, and possible use at a delayed release relay for relay 1 16.

Although the power supply has been indicated throughout by the same symbol as the AC. supply, it will be appreciated that the relay circuitry could employ a direct current supply if desired, and that different voltages may be employed for the signal circuitry and other parts of the circuitry if desired. T he AC. and DC. supplies may be with respect to ground or negative return.

Although the transmitter-receiver units and the like have been described and illustrated in terms of radar or of microwaves in one preferred form, such terms are understood to include supersonic air Waves and well-known directive electrical-acoustic transducers therefor, as both forms of vehicle detectors are well-known in the art, and the present invention relates to the directional detection and indication or alarm system employing the dual beams rather than in the vehicle detector alone.

The relays 19 and 22' may be a part of radar unit 4 or of the Doppler detection circuitry thereof, whether such circuitry is actually in the overhead radiator-receiver unitor remotely located at the side of the road for example, and correspondingly the relays 36 and 3-9 may be a part of radar unit 5 or of its Doppler detection circuitry, instead of closely coupled to the direction locking circuit and remaining circuitry of FIG. 3 as illustrated.

The inputs to these respective relays 19, 22, 36 and 39 is preferably in the form of a direct current provided in response to the respective Doppler high or low frequencies in the radar units or detection circuitry, as indicated in the Barker Patents 2,965,893 and 3,059,232 for example.

The alarm devices 62 and 69 may obviously include audible alarms in addition to visual alarms, if desirable.

Although a preferred form of a system according to the invention has been described and illustrated and certain variations in the system or parts thereof have been pointed out above, it will be understood by those skilled in the art that numerous variations in the system or in the circuitry, or substitution of equivalent elements for various parts of the system may be made without departing from the spirit of the invention.

We claim:

1. Apparatus for indicating trafiic moving in a controlled zone along a trailic lane in a direction opposed to a pre-determined direction, including indicator means for warning of said opposed direction tralfic when actuated, a Doppler detector for each end of said zone for detect ing traffic moving through the associated end of said zone, said detectors each including a low frequency Doppler detection circuit and a high frequency Doppler detection circuit, means coupled with each said detector for actuating said indicator means in response to low frequency input in said detector, a direction locking circuit coupled with each said detector and with said actuating means for maintaining said indicator means actuated and for causing the actuating means for the other of said detectors to become ineffective to so actuate said indicator means upon low frequency actuation of one of said detectors, predetermined direction circuit means coupled to said direction locking circuit and to said indicator means for preventing actuation of said indicator means by said low frequency in said pre-determined direction, and releasing means coupled to each of said high frequency circuits for releasing said direction locking circuit in response to a high frequency input.

2. The apparatus of claim 1 in which said releasing means includes a timing circuit coupled to said high frequency circuits to be operated by a high frequency signal therein to so release said direction locking circuit after a time period.

3. The apparatus of claim 2 and including means coupled to each of said low frequency circuits to be operated by a low frequency signal therein to disable said timing circuit.

4. Apparatus for maintaining directional control of traffic in a reversible traffic lane with a predetermined traflic direction, including a pair of beam radar detection units, the beams of said units being directed at said lane at an angle in opposing divergent directions, Doppler circuitry coupled to each of said units for producing high and low frequency Doppler signals in response to motion of vehicles within the beams of said units, traffic warning means associated with said lane for warning vehicles moving in said lane in a direction opposite to said predetermined direction when actuated, a direction locking circuit having individual directional outputs for the respective directions for actuating said traflic warning means, said locking circuit maintaining one said directional output for actuating said warning means and blocking operation of said other directional output in said locking circuit during its period of said actuation, a low frequency input circuit coupled to said units for actuating the direction locking circuit for one of the respective outputs upon receipt of a low frequency Doppler signal from one of said units, a timing circuit for releasing said direction locking circuit after a predetermined time interval, and a high frequency input circuit associated with said units for actuating said timing circuit upon receipt of a high frequency Doppler signal from the other of said units.

5. The apparatus of claim 4, including means coupled with each of said low frequency input circuits to disable said timing circuit in the event of actuation of either of said low frequency input circuits during said timing period.

6. Traific control apparatus for detecting and controlling direction of trafiic flow in a detection zone in a trafiic lane adapted for predetermined flow direction in either of two opposite directions, including a pair of beam detectors, one for each end of said detection zone, each of said beam detectors producing a high frequency and a low frequency Doppler output in response to speed of vehicle movement relative to said detectors, a low frequency input circuit for each direction operated by its respective said low frequency output, a high frequency input circuit for each direction operated by its respective said high frequency output, a Warning circuit for warning of traflic flow in a direction opposite to said predetermined direction, a direction locking circuit for each direction actuated by its respective low frequency input circuit for actuating said Warning circuit and maintaining it in actuated condition, each said locking circuit upon actuation disabling the said locking circuit for the other direction, and said high fre quency input circuit releasing said locking circuits in response to receipt of a signal from said high frequency output.

7. The apparatus of claim 6 including a timing circuit associated with said high frequency input circuits for delaying the release of said locking circuit for a predetermined time period after said receipt of a signal from said high frequency output, and a low frequency hold circuit for disabling said timing circuit upon receipt of a signal from either of said low frequency outputs.

8. A system for indicating traffic moving in a controlled zone of a traffic lane in a direction opposite to a predetermined direction, including a direction circuit, means for warning of opposite direction traffic, a Doppler radar detector by each end of said zone for detecting traffic moving through said zone and producing high and low Doppler frequencies in response thereto, a direction locking circuit coupled with each Doppler detector and actuated by low frequency Doppler signals received by said respective detectors, said locking circuits actuating said warning means in response to said low frequency signals and in association with said direction circuit, and means in each said locking circuit for disabling said other locking circuit while said first locking circuit is actuated, and a high frequency release circuit actuated by said high frequency signals received by said detectors to release said locking circuit as said trafiic leaves said zone, whereby said warning means will not be operated when traffic passes through said zone in said pre-deterrnined direction.

9. A system as in claim 8 in which said pre-determined detection is selectable for either direction and in which said warning means includes directional warning means individual to each direction for warning of traffic proceeding in the respective direction, and in which said system includes means coupling said direction circuit and said locking circuit to the respective directional warning means for so operating the directional warning means only for the direction against the pre-deterrnined direction.

10. A bi-directional vehicular traffic warning system for a reversible vehicular traflic lane for traffic movement in but one predetermined direction at a given time, including a pair of oppositely-directed Doppler beam detectors, each of said detectors producing a high and low frequency output signal in accordance with the movement of a vehicle relative to the detector, a Warning circuit for each traffic direction, a direction locking circuit responsive to said low frequency signals for controlling said Warning circuits in response to their respective said low frequency outputs, said locking circuit being selfinterlocked to prevent actuation of the other of said Warning circuits while said first warning circuit is actuated, a release circuit associated with said locking circuit to release same in response to one of said high frequency signals, and a direction control circuit to prevent actuation of said warning circuit when traific is moving in said predetermined direction.

11. A bi-directional traflic indication system for use on a reversible trafiic lane having a traffic direction indication zone, said system including a pair of trafiic detectors positioned to face in opposing directions in said zone and each having outer and inner detection areas, each detector producing a signal in response to vehicle movement in its outer detection area and a signal in response to vehicle movement in its inner detection area, a directional locking circuit for receiving said inner area signals from but one detector at a time to produce a continuous directional output corresponding to said first received signal, said direction locking circuit including an interlocking circuit for rendering said direction locking circuit unresponsive to an inner area signal from the other of said traflic detectors while producing said continuous directional output, an outer area input circuit and means coupled with said outer area input circuit and with said direction locking circuit to interrupt the directional output operation of said directional locking circuit in response to an outer area signal from said other of said trafiic detectors, and a timing circuit coupled to said outer area input circuit to be operated in response to an outer area signal in said outer area input circuit and coupled to said interrupting means to delay the operation of said interrupting means for a predetermined time interval, after receipt of said outer area signal.

12. The system of claim 11 including a disabling circuit coupled into said timing circuit for stopping its timing operation in response to receipt during said time interval of an inner area signal in said direction locking circuit.

13. A bidirectional traffic control system for monitoring traffic direction in a trailic lane, including a pair of oppositely-faced traffic detectors responsive to vehicular trafi'ic in their respective detection zones to produce output signals corresponding to low speed vehicle movement in said zones and corresponding to high speed vehicle movement in the outer areas of said zones, said detection zones being adjacent to one another along the traffic lane, a trafiic direction monitoring signal circuit, a control circuit responsive to said low speed signals to actuate said monitoring signal circuit for a direction dependent upon the detector first producing said low speed signal, said control circuit including a locking circuit to lock each said monitoring signal circuit in actuated condition, said control circuit including means to make low speed signals from said other detector ineffective to actuate said monitoring signal circuit while said locking circuit is operative, and a release circuit responsive to said high speed signals to release said locking circuit a pre-determined time interval after said receipt of a said high speed signal.

14. The system of claim 13 including a hold circuit responsive to said low speed signals to prevent operation of said release circuit if a low speed signal is received during said time interval.

15. The system of claim 13 in which said detectors include transmitter-receiver means for high frequency waves utilizing Doppler detection.

References Cited by the Examiner UNITED STATES PATENTS 3,126,522 3/1964 Fieser 340-39 CHESTER L. JUSTUS, Primary Examiner.

T. H. TUBBESING, Assistant Examiner. 

6. TRAFFIC CONTROL APPARATUS FOR DETECTING AND CONTROLLING DIRECTION OF TRAFFICE FLOW IN A DETECTION ZONE IN A TRAFFIC LANE ADAPTED FOR PREDETERMINED FLOW DIRECTION IN EITHER OF TWO OPPOSITE DIRECTIONS, INCLUDING A PAIR OF BEAM DETECTORS, ONE FOR EACH END OF SAID DETECTION ZONE, EACH OF SAID BEAM DETECTORS PRODUCING A HIGH FREQUENCY AND A LOW FREQUENCY DOPPLER OUTPUT IN RESPONSE TOP SPEED OF VEHICLE MOVEMENT RELATIVE TO SAID DETECTORS, A LOW FREQUENCY INPUT CIRCUIT FOR EACH DIRECTION OPERATED BY ITS RESPECTIVE SAID LOW FREQUENCY OUTPUT, A HIGH FREQUENCY INPUT CIRCUIT FOR EACH DIRECTION OPERATED BY ITS RESPECTIVE SAID HIGH FREQUENCY OUTPUT, A WARNING CIRCUIT FOR WARNING OF TRAFFIC FLOW IN A DIRECTION OPPOSITE TO SAID PREDETERMINED DIRECTION, A DIRECTION LOCKING CIRCUIT FOR EACH DIRECTION ACTUATED BY ITS RESPECTIVE LOW FREQUENCY INPUT CIRCUIT FOR ACTUATING SAID WARNING CIRCUIT AND MAINTAINING IT IN ACTUATED CONDITION, EACH SAID LOCKING CIRCUIT UPON ACTUATION DISABLING THE SAID LOCKING CIRCUIT FOR THE OTHER DIRECTION, AND SAID HIGH FREQUENCY INPUT CIRCUIT RELEASING SAID LOCKING CIRCUITS IN RESPONSE TO RECEIPT OF A SIGNAL FROM SAID HIGH FREQUENCY OUTPUT. 